From 7427a9137f60de961b6331d0922a3f03da0d1890 Mon Sep 17 00:00:00 2001
From: Simon Willison <swillison@gmail.com>
Date: Wed, 22 Sep 2021 13:20:04 -0700
Subject: [PATCH] Output [] in JSON mode if no rows, closes #328

---
 sqlite_utils/cli.py |  3 +++
 tests/test_cli.py   | 13 ++++++++++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/sqlite_utils/cli.py b/sqlite_utils/cli.py
index 10a11c6..5217965 100644
--- a/sqlite_utils/cli.py
+++ b/sqlite_utils/cli.py
@@ -2225,6 +2225,9 @@ def output_rows(iterator, headers, nl, arrays, json_cols):
         )
         yield line
         first = False
+    if first:
+        # We didn't output any rows, so yield the empty list
+        yield "[]"
 
 
 def maybe_json(value):
diff --git a/tests/test_cli.py b/tests/test_cli.py
index a6ddca0..47920c6 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -994,6 +994,13 @@ def test_query_json(db_path, sql, args, expected):
     assert expected == result.output.strip()
 
 
+def test_query_json_empty(db_path):
+    result = CliRunner().invoke(
+        cli.cli, [db_path, "select * from sqlite_master where 0"]
+    )
+    assert result.output.strip() == "[]"
+
+
 LOREM_IPSUM_COMPRESSED = (
     b"x\x9c\xed\xd1\xcdq\x03!\x0c\x05\xe0\xbb\xabP\x01\x1eW\x91\xdc|M\x01\n\xc8\x8e"
     b"f\xf83H\x1e\x97\x1f\x91M\x8e\xe9\xe0\xdd\x96\x05\x84\xf4\xbek\x9fRI\xc7\xf2J"
@@ -2098,7 +2105,11 @@ _TRIGGERS_EXPECTED = (
 
 @pytest.mark.parametrize(
     "extra_args,expected",
-    [([], _TRIGGERS_EXPECTED), (["articles"], _TRIGGERS_EXPECTED), (["counter"], "")],
+    [
+        ([], _TRIGGERS_EXPECTED),
+        (["articles"], _TRIGGERS_EXPECTED),
+        (["counter"], "[]\n"),
+    ],
 )
 def test_triggers(tmpdir, extra_args, expected):
     db_path = str(tmpdir / "test.db")